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GCOS Atmospheric Upper Air ECV: Earth Radiation Budget
Contributing Networks & Status

 
The Earth Radiation Budget (ERB) measures the overall balance between the incoming energy from the sun and the outgoing thermal (longwave) and reflected (shortwave) energy from the Earth. It can only be measured from space, and continuity of observations is an essential issue. The radiation balance at the top of the atmosphere is the basic radiative forcing of the climate system. Measuring its variability in space and time over the globe provides insight into the overall response of the system to this forcing. The satellite measurements include solar irradiance observations as well as the broadband directional measurements of reflected solar and outgoing longwave radiation.  At least one dedicated satellite ERB mission should be operating at any one time. Satellite observations should be continued without interruption, and operational plans should provide for overlap so that accuracy and resolution issues are resolved to meet climate requirements. This should be a continuing priority for CEOS and CGMS in their planning process. The requirement for this overlap is demonstrated in the figure below.

 

 

 
Figure 6: Observations of total solar irradiance (TSI) from a series of different instruments on satellites as indicated, along with monthly sunspot number. The vertical bar in the upper right corner shows a relative variation of 0.1% in TSI.  Absolute values are uncertain and differ in the past by as much as 9 Wm-2, and more recently systematically by around 4 Wm-2 so that continuous time series are only made possible by overlapping measurements from different satellites. (Source:  http://spot.colorado.edu/~koppg/TSI accessed 24 September 2009). 
 
(Source: WMO/IOC Implementation Plan for the Global Observing System for Climate in Support of the UNFCCC (2010 Update) GCOS-138, GOOS-184, GTOS-76, WMO-TD/No. 1523)
 

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